Gregory chamitoff - Academia.edu (original) (raw)

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Papers by Gregory chamitoff

IFAC Proceedings Volumes, Sep 1, 1994

This paper presents a trajectory optimizatIon algorithm that is applicable to real-time autonom o... more This paper presents a trajectory optimizatIon algorithm that is applicable to real-time autonom o us gUidance for the landing of a remotely piloted vehicle. Admissible paths are quickly generated by a l\vo-stage optimizatIon. where constraint satisfaction takes precedence over optimality. Asymptotic convergence IS achi e ved by r~stflctrng the class of constrarnt functions , and selecting a path parameterization , su c h that the cost function is positive definite in the parameter errors. Parameter estimates are Inltlailzed by solvrng a rdaxed problem, and subsequent estImates are restflcted to a subspace that enforces th e boundary conditIons A SImple numerical example IS given to Illustrate this approach .

43rd COSPAR Scientific Assembly. Held 28 January - 4 February, 2021

AIAA Scitech 2020 Forum, Jan 5, 2020

We present UnrealNavigation; an integrated software platform for testing Simultaneous Localizatio... more We present UnrealNavigation; an integrated software platform for testing Simultaneous Localization and Mapping (SLAM) algorithms for autonomous robotic navigation. The framework , which is part of a Virtual Reality simulation in space environments is designed to allow rapid testing of autonomous navigation algorithm components. The architecture is designed with a plug-and-play style adaptability in mind, allowing for a wide range of uses and rapid development. Two approaches to SLAM will be demonstrated in the novel simulation framework , utilizing a game development engine, Unreal, connected by the Robotic Operating System (ROS). Comparison of these two algorithms was enabled through the simulation framework created. The different approaches authenticate the ability to integrate a holistic algorithm system or separate components into the framework.

AIAA SCITECH 2023 Forum, Jan 23, 2023

In this paper, we utilized a bi-directional thrust quadrotor with manipulators to mimic a bat’s u... more In this paper, we utilized a bi-directional thrust quadrotor with manipulators to mimic a bat’s upside-down perching maneuver. This "perch and watch" capability could be beneficial to some specific mission involved extended endurance, such as monitoring wild animals in a natural reserve. This capability also avoids the downwash effect that commonly encountered during an upright perching. The bi-directional thrust is achieved by the dedicated Electric Speed Controller (ESC) firmware which could drive motor bi-directionally during the flight and with nearly symmetric fixed pitch propeller. This method of generating bi-directional thrust has a noticeable delay compared to a variable pitch propeller mechanism, thus a compensation strategy is adopted to minimize the delay in the process of reversing the propeller. So the altitude loss is minimized when a half flip maneuver is conducted. We also noticed that an inverted quadrotor generates more thrust compared to the upright configuration due to frame obstruction, thus controller gains also need to be compensated for accurate trajectory tracking. A customized offboard control method is developed to achieve this perching upside maneuvers with a motion capture system. Finally, a feasible perching trajectory is generated and the test result is presented.

AIAA SCITECH 2023 Forum, Jan 19, 2023

2022 IEEE Aerospace Conference (AERO), Mar 5, 2022

Algorithms for spacecraft attitude estimation utilizing input from star trackers are often tested... more Algorithms for spacecraft attitude estimation utilizing input from star trackers are often tested in a limited simulation environment. This paper presents an interactive virtual reality testbed for experimenting with attitude determination in any user-defined scenario. Specifically, a database containing a star catalog and initial conditions are fed into a developed star tracker model. This model uses Gaussian convolution to create an accurate output based on the field of view and simulated dynamics the star tracker is experiencing. A general space vehicle rigid body dynamics model has been implemented, allowing the user to plug in any sort of attitude dynamics. and pp image distortion, stellar aberration, field of view, and rigid body dynamics can be specified by the user. A high-resolution star map has been generated for use in SpaceCRAFT, which will be used as a testbed for the generated camera model. The camera model provides a view of the sky from the point of view of the satellite, allowing the user to modify the parameters needed until a solution to the attitude problem is solved. A virtual reality interface is provided for precise satellite component placement, along with custom analysis tools. This paper presents the development of the overall system and verifies its potential use in the optimization and test of star tracker hardware.

2022 IEEE Aerospace Conference (AERO), Mar 5, 2022

AIAA Scitech 2021 Forum, Jan 4, 2021

Frontiers in Physiology, Oct 11, 2022

Long duration spaceflight missions will require novel exercise systems to protect astronaut crew ... more Long duration spaceflight missions will require novel exercise systems to protect astronaut crew from the detrimental effects of microgravity exposure. The SPRINT protocol is a novel and promising exercise prescription that combines aerobic and resistive training using a flywheel device, and it was successfully employed in a 70-day bed-rest study as well as onboard the International Space Station. Our team created a VR simulation to further augment the SPRINT protocol when using a flywheel ergometer training device (the Multi-Mode Exercise Device or M-MED). The simulation aspired to maximal realism in a virtual river setting while providing real-time biometric feedback on heart rate performance to subjects. In this pilot study, five healthy, male, physically-active subjects aged 35 ± 9.0 years old underwent 2 weeks of SPRINT protocol, either with or without the VR simulation. After a 1-month washout period, subjects returned for a subsequent 2 weeks in the opposite VR condition. We measured physiological and cognitive variables of stress, performance, and well-being. While physiological effects did not suggest much difference with the VR condition over 2 weeks, metrics of motivation, affect, and mood restoration showed detectable differences, or trended toward more positive outcomes than exercise without VR. These results provide evidence that a well-designed VR "exergaming" simulation with biometric feedback could be a beneficial addition to exercise prescriptions, especially if users are exposed to isolation and confinement.

AIAA Scitech 2020 Forum, Jan 5, 2020

2022 IEEE Aerospace Conference (AERO)

47th International Conference on Environmental Systems, Jul 16, 2017

2021 IEEE Aerospace Conference (50100), 2021

This paper proposes a new method for robotic teleoperation scenarios with significant time delay ... more This paper proposes a new method for robotic teleoperation scenarios with significant time delay utilizing Extended Reality (XR) technologies, specifically for Lunar base assembly and maintenance. Traditional teleoperation interfaces interpret commands sent through a desktop computer screen and are limited in providing spatial awareness cues. Additionally, the software often has difficulty in accounting for a time delay or providing intuitive techniques for human-robot interaction (HRI). This paper presents a new XR interface for robotic teleoperation using a predictive 3D simulated virtual environment developed using the SpaceCRAFT platform. SpaceCRAFT is a multiuser Virtual Reality (VR) and Augmented Reality (AR) systems engineering toolbox software that allows for worldwide collaboration on design and test of space systems. SpaceCRAFT provides the operator a virtual interface to the robot represented through three different states, a Virtual Command State (VCS), Predicted Current State (PCS), and Time Delayed State (TDS). To improve situational awareness and the PCS representation of the robot, SpaceCRAFT processes LIDAR and RGB camera data to create a constantly updating 3D point cloud representation of the remote environment. An experiment involving teleoperation of a 3D printed robotic manipulator was run, with a simulated time delay similar to that between the Earth and the Moon. Results demonstrate that the predictive approach provides an effective and flexible method of robot teleoperation that helps achieve successful task completion, even with a large time delay.

IFAC Proceedings Volumes, Sep 1, 1994

This paper presents a trajectory optimizatIon algorithm that is applicable to real-time autonom o... more This paper presents a trajectory optimizatIon algorithm that is applicable to real-time autonom o us gUidance for the landing of a remotely piloted vehicle. Admissible paths are quickly generated by a l\vo-stage optimizatIon. where constraint satisfaction takes precedence over optimality. Asymptotic convergence IS achi e ved by r~stflctrng the class of constrarnt functions , and selecting a path parameterization , su c h that the cost function is positive definite in the parameter errors. Parameter estimates are Inltlailzed by solvrng a rdaxed problem, and subsequent estImates are restflcted to a subspace that enforces th e boundary conditIons A SImple numerical example IS given to Illustrate this approach .

43rd COSPAR Scientific Assembly. Held 28 January - 4 February, 2021

AIAA Scitech 2020 Forum, Jan 5, 2020

We present UnrealNavigation; an integrated software platform for testing Simultaneous Localizatio... more We present UnrealNavigation; an integrated software platform for testing Simultaneous Localization and Mapping (SLAM) algorithms for autonomous robotic navigation. The framework , which is part of a Virtual Reality simulation in space environments is designed to allow rapid testing of autonomous navigation algorithm components. The architecture is designed with a plug-and-play style adaptability in mind, allowing for a wide range of uses and rapid development. Two approaches to SLAM will be demonstrated in the novel simulation framework , utilizing a game development engine, Unreal, connected by the Robotic Operating System (ROS). Comparison of these two algorithms was enabled through the simulation framework created. The different approaches authenticate the ability to integrate a holistic algorithm system or separate components into the framework.

AIAA SCITECH 2023 Forum, Jan 23, 2023

In this paper, we utilized a bi-directional thrust quadrotor with manipulators to mimic a bat’s u... more In this paper, we utilized a bi-directional thrust quadrotor with manipulators to mimic a bat’s upside-down perching maneuver. This "perch and watch" capability could be beneficial to some specific mission involved extended endurance, such as monitoring wild animals in a natural reserve. This capability also avoids the downwash effect that commonly encountered during an upright perching. The bi-directional thrust is achieved by the dedicated Electric Speed Controller (ESC) firmware which could drive motor bi-directionally during the flight and with nearly symmetric fixed pitch propeller. This method of generating bi-directional thrust has a noticeable delay compared to a variable pitch propeller mechanism, thus a compensation strategy is adopted to minimize the delay in the process of reversing the propeller. So the altitude loss is minimized when a half flip maneuver is conducted. We also noticed that an inverted quadrotor generates more thrust compared to the upright configuration due to frame obstruction, thus controller gains also need to be compensated for accurate trajectory tracking. A customized offboard control method is developed to achieve this perching upside maneuvers with a motion capture system. Finally, a feasible perching trajectory is generated and the test result is presented.

AIAA SCITECH 2023 Forum, Jan 19, 2023

2022 IEEE Aerospace Conference (AERO), Mar 5, 2022

Algorithms for spacecraft attitude estimation utilizing input from star trackers are often tested... more Algorithms for spacecraft attitude estimation utilizing input from star trackers are often tested in a limited simulation environment. This paper presents an interactive virtual reality testbed for experimenting with attitude determination in any user-defined scenario. Specifically, a database containing a star catalog and initial conditions are fed into a developed star tracker model. This model uses Gaussian convolution to create an accurate output based on the field of view and simulated dynamics the star tracker is experiencing. A general space vehicle rigid body dynamics model has been implemented, allowing the user to plug in any sort of attitude dynamics. and pp image distortion, stellar aberration, field of view, and rigid body dynamics can be specified by the user. A high-resolution star map has been generated for use in SpaceCRAFT, which will be used as a testbed for the generated camera model. The camera model provides a view of the sky from the point of view of the satellite, allowing the user to modify the parameters needed until a solution to the attitude problem is solved. A virtual reality interface is provided for precise satellite component placement, along with custom analysis tools. This paper presents the development of the overall system and verifies its potential use in the optimization and test of star tracker hardware.

2022 IEEE Aerospace Conference (AERO), Mar 5, 2022

AIAA Scitech 2021 Forum, Jan 4, 2021

Frontiers in Physiology, Oct 11, 2022

Long duration spaceflight missions will require novel exercise systems to protect astronaut crew ... more Long duration spaceflight missions will require novel exercise systems to protect astronaut crew from the detrimental effects of microgravity exposure. The SPRINT protocol is a novel and promising exercise prescription that combines aerobic and resistive training using a flywheel device, and it was successfully employed in a 70-day bed-rest study as well as onboard the International Space Station. Our team created a VR simulation to further augment the SPRINT protocol when using a flywheel ergometer training device (the Multi-Mode Exercise Device or M-MED). The simulation aspired to maximal realism in a virtual river setting while providing real-time biometric feedback on heart rate performance to subjects. In this pilot study, five healthy, male, physically-active subjects aged 35 ± 9.0 years old underwent 2 weeks of SPRINT protocol, either with or without the VR simulation. After a 1-month washout period, subjects returned for a subsequent 2 weeks in the opposite VR condition. We measured physiological and cognitive variables of stress, performance, and well-being. While physiological effects did not suggest much difference with the VR condition over 2 weeks, metrics of motivation, affect, and mood restoration showed detectable differences, or trended toward more positive outcomes than exercise without VR. These results provide evidence that a well-designed VR "exergaming" simulation with biometric feedback could be a beneficial addition to exercise prescriptions, especially if users are exposed to isolation and confinement.

AIAA Scitech 2020 Forum, Jan 5, 2020

2022 IEEE Aerospace Conference (AERO)

47th International Conference on Environmental Systems, Jul 16, 2017

2021 IEEE Aerospace Conference (50100), 2021

This paper proposes a new method for robotic teleoperation scenarios with significant time delay ... more This paper proposes a new method for robotic teleoperation scenarios with significant time delay utilizing Extended Reality (XR) technologies, specifically for Lunar base assembly and maintenance. Traditional teleoperation interfaces interpret commands sent through a desktop computer screen and are limited in providing spatial awareness cues. Additionally, the software often has difficulty in accounting for a time delay or providing intuitive techniques for human-robot interaction (HRI). This paper presents a new XR interface for robotic teleoperation using a predictive 3D simulated virtual environment developed using the SpaceCRAFT platform. SpaceCRAFT is a multiuser Virtual Reality (VR) and Augmented Reality (AR) systems engineering toolbox software that allows for worldwide collaboration on design and test of space systems. SpaceCRAFT provides the operator a virtual interface to the robot represented through three different states, a Virtual Command State (VCS), Predicted Current State (PCS), and Time Delayed State (TDS). To improve situational awareness and the PCS representation of the robot, SpaceCRAFT processes LIDAR and RGB camera data to create a constantly updating 3D point cloud representation of the remote environment. An experiment involving teleoperation of a 3D printed robotic manipulator was run, with a simulated time delay similar to that between the Earth and the Moon. Results demonstrate that the predictive approach provides an effective and flexible method of robot teleoperation that helps achieve successful task completion, even with a large time delay.